1. Field of the Invention
The present invention relates generally to the field of alarm systems for securing building openings including doors and windows. More specifically it relates to a self-contained screen alarm apparatus which mounts as a complete, single unit within a building opening in place of a conventional screen. The screen alarm apparatus provides the same barrier against insect entry afforded by conventional screens, but also sounds an alarm if the screen is ripped apart or pulled out of the building opening. The apparatus includes a screen and frame of ordinary design where the edges of the screen are fitted into a spline channel in the frame, and a rubber spline member is pressed into the spline channel to hold the screen edges in place. The apparatus adds to this construction a loop of current carrying wire woven through the screen wire in an elongated sine wave pattern extending from the top to the bottom of the screen. The ends of this detection wire are connected to terminals on a detection and sounder assembly secured within a corner of the screen frame. Breakage of the detection wire activates an alarm within the detection and sounder assembly. The assembly includes a triangular mounting plate secured in a corner of the screen frame and an assembly module which removably attaches to the plate. The two detection wire terminals are attached to the plate. The module contains a battery, a tilt switch, internal and external combination switches, a circuit board, an alarm sounder and interconnecting module circuitry. The alarm sounder is activated by either a discontinuity in the detection wire or by tilt of the apparatus substantially out of the vertical plane, thereby opening the tilt switch. Once activated the alarm sounder is locked in an activated mode until deactivated by the apparatus user.
2. Description of the Prior Art
There have long been alarm systems and devices for securing doors and windows of buildings against unwanted entry.
Riordan, U.S. Pat. No. 5,005,000, issued on Apr. 2, 1991, discloses an alarm screen kit. The Riordan kit includes a sheet of nonconductive screen mesh, a conductive detection wire for interweaving into the screen mesh and framing members for securing the edges of screen mesh. These parts are provided disassembled in a tubular container. The installation procedure includes the step of electrically coupling the detection wire to a separate alarm device. A problem with Riordan is that installation requires a technical knowledge sufficient to connect the wiring between the screen and the alarm device, as well as to assemble the remainder of the kit. Another problem with Riordan is that, since the power source and sounding element are separate from the screen structure, alarm disconnection and deactivation are a serious risk.
Abramson, U.S. Pat. No. 4,814,750, issued on Mar. 21, 1989, reveals a window screen alarm. Abramson includes a screen mesh having an interwoven detection wire connected to a separate alarm speaker and an optional separate alarm light. A magnetic sensor is provided the edge of the screen frame to activate the alarm upon removal of the screen from the frame. Williams, U.S. Pat. No. 4,293,778, issued on Oct. 6, 1981, teaches an anti-theft screen construction substantially similar to that of Abramson. A reed switch is provided at the screen periphery which is activated by a magnet mounted to the window frame adjacent the reed switch. The problems of Riordan are presented by Abramson and Williams.
Mutton, et al., U.S. Pat. No. 4,146,293, issued on Mar. 27, 1979, discloses an entry detection screen. For one embodiment of Mutton, et al., double wires are woven through the screen and connected to two series circuits. The double wires may be twisted to make tracing the individual circuits difficult for an intruder. The wires connect to a separate alarm sounding device. The problems of Riordan are again presented.
Dunn, et al., U.S. Pat. No. 3,696,373, issued on Oct. 3, 1972, reveals an electric alarm screen. The Dunn et al. screen detection circuit is made up of clusters of conductive detection wires passing together between alternating conductive plates secured to the screen frame. The alarm device and detectors are separate from the screen, and the screen of one window is wired to the screen of the next window. Dunn et al. presents the problems of Riordan, in addition to the problems of complexity, bulk and substantial expense to manufacture.
Willson, U.S. Pat. No. 3,051,935, issued on Aug. 28, 1962, teaches a protective screen having a detection wire circuit woven through it. Contact points in electrical communication with the detection wire are provided at the edge of the frame for connection together in pairs through a conducting bar mounted on the building structure. An separate alarm circuit is activated when the detection wire circuit is opened. The problems of Riordan are presented.
Kohler, U.S. Pat. No. 1,712,771, issued on May 14, 1929, discloses a double screen burglar alarm. An electrically insulated frame is provided having frame members about one quarter inch thick. A conductive screen is secured to each side of the frame, so that the two screens are separated about one quarter inch. Each screen is wired to an alarm circuit, so that bringing the screens into contact, such as by pressing against one screen so that it touches the other, activates the alarm circuit. A problem with Kohler is that the apparatus requires two screen sheets, substantially increasing the cost. Another problem is that one who is not an intruder may simply touch the screen in an inquisitive manner and activate the alarm. Children may do so for their amusement. And, once again, the problems of Riordan are presented.
Siegerdt, U.S. Pat. No. 1,630,808, issued on May 31, 1927, reveals an alarm device to keep children from falling out of windows of apartments. Siegerdt employs the double screen design of Kohler, except that the second screen fits into a recess in the frame. The problems of Kohler are again presented.
Galerman, U.S. Pat. No. 1,452,500, issued on Apr. 24, 1923, discloses a burglar alarm apparatus. Galerman substantially includes a typical insect screen and detection wire arrangement. Opposing poles of a battery are connected to two wires, and contact of these two wires activates the alarm. These two wires are separated by push buttons and are bent into a number of convolutions to cover a window sash or similar structure. An attempt to break the window is said to bring these two wires into contact to sound the alarm. Galerman presents the problems of Riordan, in addition to being primitive and complex.
Arnold, U.S. Pat. No. 585,171, issued on Jun. 29, 1897, teaches a burglar alarm system. Arnold includes a sliding cover adapted to be placed over a building opening. The cover has a mounting which permits ready removal of the cover from its normal place. A circuit closing device is adapted to be operated by the cover when the cover is shifted from its normal plane, to activate a burglar alarm. A problem with Arnold is that it is very complex and primitive. Arnold also presents the problems of Riordan.
Gill, U.S. Pat. No. 535,100, issued on Mar. 5, 1895, teaches a burglar alarm for glass doors. A conductive film or strip is bonded to the glass along the window periphery and connects at two ends to an external alarm device. Gill presents the problems of Riordan in addition to being poorly suited to screen adaptations. A conductor along the periphery of a screen would not necessarily detect a tear in the middle of the screen.
It is thus an object of the present invention to provide a building opening screen alarm apparatus which is entirely self-contained, so that it does not rely on external power sources or an external apparatus.
It is another object of the present invention to provide such an apparatus which is installed in the same manner as a conventional framed screen is installed into a window opening thus requiring no special effort, skills or tools, and which stacks in storage as compactly as conventional framed screens.
It is still another object of the present invention to provide such an apparatus in which the electronic elements are contained within a conveniently removable module which can be sent away for repairs while the screen remains installed in the building opening, continuing to serve as an insect barrier.
It is finally an object of the present invention to provide such an apparatus which is universally adaptable, fitting into virtually any preexisting screen mounting structure, and into which a preexisting screen can be adapted by merely adding the detection wire, the mounting plate and the module.